Double- headed piston type swash plate compressor

ABSTRACT

A double-headed piston type swash plate compressor has a first abutting portion provided between a first housing member and a first cylinder block and a second abutting portion provided between a second housing member and a second cylinder block. The first abutting portion is located inside a first circumcircle of the group of first cylinder bores and causes the first housing member and the first cylinder block to make metal-to-metal contact. The second abutting portion is located inside a second circumcircle of the group of second cylinder bores and causes the second housing member and the second cylinder block to make metal-to-metal contact.

BACKGROUND OF THE INVENTION

The present invention relates to a double-headed piston type swash plate compressor.

Japanese Laid-Open Patent Publication No. 9-203375 discloses a conventional double-headed piston type swash plate compressor (hereinafter, simply referred to as a compressor). This compressor includes a first cylinder block, a first housing member, a second cylinder block, and a second housing member. The first and second cylinder blocks and the first and second housing members are generally made of metal.

The first cylinder block includes first cylinder bores. The first housing member is secured to the first cylinder block at the rear end with a first valve plate in between. The second cylinder block is secured to the first cylinder block at the front end. The second cylinder block and the first cylinder block define a swash plate chamber. The second cylinder block includes second cylinder bores, each of which constitutes a pair with one of the first cylinder bores. The second housing member is secured to the second cylinder block at the front end with a second valve plate in between.

The first valve plate extends to a position short of the outer peripheries of the first housing member and the first cylinder block to be held by the first housing member and the first cylinder block. The outer periphery of the first housing member and the outer periphery of the first cylinder block directly contact each other, and the boundary between the first housing member and the first cylinder block is sealed by an O-ring. The second valve plate also extends to a position short of the outer peripheries of the second housing member and the second cylinder block to be held by the second housing member and the second cylinder block. The outer periphery of the second housing member and the outer periphery of the second cylinder block directly contact each other, and the boundary between the second housing member and the second cylinder block is sealed by an O-ring.

The compressor also includes a drive shaft, a swash plate, double-headed pistons, a first thrust bearing, and second thrust bearing.

The drive shaft is rotationally supported by the first cylinder block and the second cylinder block. The swash plate is rotated in the swash plate chamber by rotation of the drive shaft. The double-headed pistons are reciprocated in the first cylinder bores and the second cylinder bores by rotation of the swash plate. The first thrust bearing is located between the first cylinder block and the drive shaft. The second thrust bearing is located between the second cylinder block and the drive shaft. The first and second thrust bearings are preloaded.

When this compressor is operated, compression reaction force due to reciprocation of the double-headed pistons is transmitted to the drive shaft via the swash plate and applies thrust to the drive shaft. The first and second thrust bearings bear the thrust to suppress vibrations and accompanying noise during operation.

Compressors are generally desired to be reduced in size and manufacturing costs. In this regard, the above described conventional compressor may have a gasket on the first valve plate, and the gasket may be held between the first housing member and the first cylinder block to seal the boundary between the first housing member and the first cylinder block. Likewise, the compressor may have another gasket on the second valve plate, and the gasket may be held between the second housing member and the second cylinder block to seal the boundary between the second housing member and the second cylinder block. These structures eliminate the necessity for the spaces for accommodating the O-rings, allowing the diameters of the first and second cylinder blocks and the first and second housing members to be reduced. Accordingly, the size and the manufacturing costs of the compressor are reduced.

In this case, a gasket is located between the first cylinder block and the first housing member, and another gasket is located between the second cylinder block and the second housing member. This is likely to lower the support stiffness in the axial direction of the drive shaft in the compressor. This may lower the preload on the first and second thrust bearings, so that the first and second bearings may fail to properly bear the thrust acting on the drive shaft. As a result, vibrations and accompanying noise during operation are increased.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide a double-headed piston type swash plate compressor that suppresses vibrations and accompanying noise during operation, while reducing the size and the manufacturing costs.

To achieve the foregoing objective and in accordance with one aspect of the present invention, a double-headed piston type swash plate compressor is provided that includes a first cylinder block, a first housing member, a first gasket, a second cylinder block, a second housing member, a second gasket, a drive shaft, a swash plate, double-headed pistons, a first thrust bearing, a second thrust bearing, a first abutting portion, and a second abutting portion. The first cylinder block is made of metal and has a plurality of first cylinder bores. The first housing member is made of metal and arranged on a first side of the first cylinder block. The first gasket is arranged between the first housing member and the first cylinder block and seals a boundary between the first housing member and the first cylinder block. The second cylinder block is made of metal and is arranged on a second side of the first cylinder block that is opposite to the first side. The second cylinder block has a plurality of second cylinder bores and, together with the first cylinder block, defines a swash plate chamber. The second housing member is made of metal. When a side of the second cylinder block that faces the first cylinder block is defined as a first side, the second housing member is arranged on a second side of the second cylinder block that is opposite to the first side. The second gasket is arranged between the second cylinder block and the second housing member and seals a boundary between the second cylinder block and the second housing member. The drive shaft is rotationally supported by the first cylinder block and the second cylinder block. The swash plate is rotational in the swash plate chamber by rotation of the drive shaft. The double-headed pistons are reciprocal in the first cylinder bores and the second cylinder bores by rotation of the swash plate. The first thrust bearing is arranged between the first cylinder block and the drive shaft and bears thrust acting on the drive shaft. The second thrust bearing is arranged between the second cylinder block and the drive shaft and bears thrust acting on the drive shaft. When a circumcircle of the group of the first cylinder bores is defined as a first circumcircle, the first abutting portion is located between the first housing member and the first cylinder block and inside the first circumcircle, and the first abutting portion causes the first housing member and the first cylinder block to make metal-to-metal contact. When a circumcircle of the group of the second cylinder bores is defined as a second circumcircle, the second abutting portion is located between the second housing member and the second cylinder block and inside the second circumcircle, and the second abutting portion causes the second housing member and the second cylinder block to make metal-to-metal contact.

Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a compressor according to one embodiment at the minimum displacement;

FIG. 2 is a cross-sectional view of the compressor according to the embodiment at the maximum displacement;

FIG. 3 is a schematic diagram showing the control mechanism of the compressor according to the embodiment;

FIG. 4 is an enlarged partial cross-sectional view showing the first housing member, the first cylinder block, and the first thrust bearing of the compressor according to the embodiment;

FIG. 5 is an enlarged partial cross-sectional view showing the second housing member, the second cylinder block, and the second thrust bearing of the compressor according to the embodiment;

FIG. 6 is an enlarged partial cross-sectional view showing the relative positional relationship among the first cylinder block, the first thrust bearing, and a first abutting portion in the compressor according to the embodiment;

FIG. 7 is an enlarged partial cross-sectional view showing the relative positional relationship among the second cylinder block, the second thrust bearing, and a second abutting portion in the compressor according to the embodiment;

FIG. 8 is an explanatory diagram of the compressor according to the embodiment, illustrating an area in which the first thrust bearing and the first cylinder block contact each other, an area in which the first thrust bearing and the drive shaft contact each other, and an area in which the first abutting portion and the first cylinder block make metal-to-metal contact;

FIG. 9 is an explanatory diagram of the compressor according to the embodiment, illustrating the area in which the first thrust bearing and the first cylinder block contact each other and the area in which the first abutting portion and the first cylinder block make metal-to-metal contact;

FIG. 10 is an explanatory diagram of the compressor according to the embodiment, illustrating an area in which the second thrust bearing and the second cylinder block contact each other, an area in which the second thrust bearing and the drive shaft contact each other, and an area in which the second abutting portion and the second cylinder block make metal-to-metal contact;

FIG. 11 is an explanatory diagram of the compressor according to the embodiment, illustrating the area in which the second thrust bearing and the second cylinder block contact each other and the area in which the second abutting portion and the second cylinder block make metal-to-metal contact;

FIG. 12 is an explanatory diagram of a compressor according to a first modification, illustrating a relative positional relationship among a first cylinder block, a first thrust bearing, and a first abutting portion; and

FIG. 13 is an explanatory diagram of a compressor according to a second modification, illustrating the relative positional relationship among a first cylinder block, a first thrust bearing, and a first abutting portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment and first and second modifications of the present invention will now be described with reference to the drawings. The compressors of the embodiment and the modifications are installed in vehicles and are each included in the refrigeration circuit in the vehicle air conditioner.

As shown in FIG. 1, a double-headed piston type swash plate compressor according to the embodiment includes a housing 1, a drive shaft 3, a swash plate 5, a link mechanism 7, double-headed pistons 9, pairs of shoes 11 a, 11 b, and an actuator 13. As shown in FIG. 3, the compressor also includes a control mechanism 15.

As shown in FIGS. 1 and 2, the housing 1 has a first housing member 17, a second housing member 19, a first cylinder block 21, and a second cylinder block 23. The first and second housing members 17, 19 and the first and second cylinder blocks 21, 23 are all made of metal, specifically an aluminum alloy.

In the present embodiment, the side on which the first housing member 17 is arranged is defined as a front side, and the side on which the second housing member 19 is arranged is defined as a rear side. The front-rear direction of the compressor is defined, accordingly.

The front side and the rear side of the first cylinder block 21 are defined as a first side and a second side, respectively. The front side and the rear side of the second cylinder block 23 are defined as a first side and a second side, respectively. That is, the side of the second cylinder block 23 that faces the first cylinder block 21 is defined as the first side, and the side opposite to the first side is defined as the second side. Thus, the first housing member 17 is located on the first side, or the front side, of the first cylinder block 21. The second housing member 19 is located on the second side, or the rear side, of the second cylinder block 23, which is opposite to the first side.

As shown in FIG. 4 in an enlarged manner, the first housing member 17 includes a housing main body 17 a, which has a cylindrical shape with a closed end, and a boss 17 b, which protrudes toward the front side from the housing main body 17 a. The boss 17 b accommodates a shaft sealing device 25. An annular first suction chamber 27 a and an annular first discharge chamber 29 a are defined in the housing main body 17 a. The first suction chamber 27 a is located in a radially inner area in the housing main body 17 a. The first discharge chamber 29 a is located radially outward of the first suction chamber 27 a in the housing main body 17 a.

The housing main body 17 a further has a first protrusion 170 at a position radially inward of the first suction chamber 27 a. That is, the first protrusion 170 is closer to the center of the housing main body 17 a than the first suction chamber 27 a. The first protrusion 170 is integrated with the housing main body 17 a. Since the first housing member 17 is made of metal as described above, the first protrusion 170 is also made of metal. The first protrusion 170 has a cylindrical shape the center of which coincides with the axis O of the drive shaft 3. The first protrusion 170 protrudes rearward over a rear end face 17 c of the housing main body 17 a. The rear end face of the first protrusion 170 is a first abutting portion 170 a. The first abutting portion 170 a is a surface that directly contacts the first cylinder block 21. The first abutting portion 170 a is a flat surface. Since the first protrusion 170 is cylindrical, the first abutting portion 170 a has an annular shape. An accommodation chamber 170 b is defined inside the first protrusion 170.

The housing main body 17 a has a first front-side communication passage 18 a. The first front-side communication passage 18 a communicates with the first discharge chamber 29 a at the front end and opens at the rear end in the rear end face 17 c of the housing main body 17 a.

As shown in FIG. 5 in an enlarged manner, the second housing member 19 has a cylindrical shape with a closed end. A part of the control mechanism 15 is arranged in the second housing member 19. An annular second suction chamber 27 b and an annular second discharge chamber 29 b are defined in the second housing member 19. The second suction chamber 27 b is located in a radially inner area in the second housing member 19. The second discharge chamber 29 b is located radially outward of the second suction chamber 27 b in the second housing member 19.

The second housing member 19 further has a second protrusion 190 at a position radially inward of the second suction chamber 27 b. That is, the second protrusion 190 is closer to the center of second housing member 19 than the second suction chamber 27 b. The second protrusion 190 is integrated with the second housing member 19. Since the second housing member 19 is made of metal as described above, the second protrusion 190 is also made of metal. The second protrusion 190 has a cylindrical shape the center of which coincides with the drive shaft axis O. The second protrusion 190 protrudes forward over a front end face 19 a of the second housing member 19. The front end face of the second protrusion 190 is a second abutting portion 190 a. The second abutting portion 190 a is a flat surface. Since the second protrusion 190 is cylindrical, the second abutting portion 190 a has an annular shape. A pressure regulation chamber 31 is defined at a position radially inward of the second protrusion 190.

Further, the second housing member 19 has a first rear-side communication passage 20 a. The first rear-side communication passage 20 a communicates with the second discharge chamber 29 b at the rear end and opens at the front end in the front end face of the second housing member 19.

As shown in FIG. 1, the first cylinder block 21 has a flat front end face 21 a and a flat rear end face 21 b. As shown in FIGS. 1 and 8, the first cylinder block 21 has five first cylinder bores 211 to 215, which extend in the drive shaft axial direction of the drive shaft 3 from the front end face 21 a to the rear end face 21 b. Each of the first cylinder bores 211 to 215 extends in the axial direction of the drive shaft 3 from the front end face 21 a to the rear end face 21 b. The first cylinder bores 211 to 215 are arranged on the same circle and spaced apart at the same angular intervals.

As shown in FIG. 4, a projection 21 c, which projects forward, is provided on the front end face 21 a. The projection 21 c has a first shaft hole 21 d for receiving the drive shaft 3. The first shaft hole 21 d accommodates a first plain bearing 22 a. First retainer grooves 21 e are recessed in the front end face 21 a to limit the maximum opening degree of first suction reed valves 391 a, which will be discussed below.

The first cylinder block 21 also includes a first recess 21 f, which communicates with the first shaft hole 21 d from the rear. The first recess 21 f is coaxial with the first shaft hole 21 d and has a larger inner diameter than the first shaft hole 21 d. An annular first recessed surface 21 g, which is recessed forward, is located in the front wall of the first recess 21 f.

A first thrust bearing 35 a is arranged in the first recess 21 f. The first thrust bearing 35 a includes a first race 351, a second race 352, rolling elements 353, which are held between the first and second races 351, 352, and a holder (not shown), which holds the rolling elements 353 between the first and second races 351, 352.

As shown in FIG. 1, the first cylinder block 21 has a first connection passage 37 a and a second front-side communication passage 18 b. The first connection passage 37 a and second front-side communication passage 18 b both extend in the drive shaft axial direction from the front end face 21 a to the rear end face 21 b. The front ends of the first connection passage 37 a and the second front-side communication passage 18 b open at the front end face 21 a of the first cylinder block 21, and the rear ends open at the rear end face 21 b of the first cylinder block 21.

The second cylinder block 23 has a flat front end face 23 a and a flat rear end face 23 b. The front end face 23 a of the second cylinder block 23 is secured to the rear end face 21 b of the first cylinder block 21 so that a swash plate chamber 33 is defined between the first and second cylinder blocks 21, 23. The swash plate chamber 33 communicates with the first recess 21 f. Accordingly, the first recess 21 f constitutes a part of the swash plate chamber 33.

As shown in FIGS. 1 and 10, the second cylinder block 23 has five second cylinder bores 231 to 235. Each of the second cylinder bores 231 to 235 extends in the drive shaft axial direction from the front end face 23 a to the rear end face 23 b. The second cylinder bores 231 to 235 are arranged on the same circle and spaced apart at the same angular intervals. The second cylinder bores 231 to 235 each face corresponding one of the first cylinder bores 211 to 215. The second cylinder bores 231 to 235 have the same outer diameter as the first cylinder bores 211 to 215.

As shown in FIG. 5, a projection 23 c, which projects toward rear of the compressor, is provided on the rear end face 23 b. An O-ring 51 a is fitted on the outer circumference of the projection 23 c. The projection 23 c has a second shaft hole 23 d for receiving the drive shaft 3. The second shaft hole 23 d accommodates a second plain bearing 22 b. Second retainer grooves 23 e are recessed in the rear end face 23 b to limit the maximum opening degree of second suction reed valves 411 a, which will be discussed below.

The second cylinder block 23 also includes a second recess 23 f, which communicates with the second shaft hole 23 d from the front side. The second recess 23 f is coaxial with the second shaft hole 23 d and has a larger inner diameter than the second shaft hole 23 d. The second recess 23 f communicates with the swash plate chamber 33 and thus constitutes a part of the swash plate chamber 33. An annular second recessed surface 23 g, which is recessed rearward, is located in the rear wall of the second recess 23 f.

A second thrust bearing 35 b is arranged in the second recess 23 f. The second thrust bearing 35 b includes a first race 354, a second race 355, rolling elements 356, which are held between the first and second races 354, 355, and a holder (not shown), which holds the rolling elements 356 between the first and second races 354, 355.

As shown in FIG. 1, the second cylinder block 23 has an outlet 230, a junction discharge chamber 239, a third front-side communication passage 18 c, a second rear-side communication passage 20 b, an inlet 330, and a second connection passage 37 b. The outlet 230 and the junction discharge chamber 239 communicate with each other. The junction discharge chamber 239 is coupled to a condenser (not shown), which constitutes a conduit, via the outlet 230. The swash plate chamber 33 is connected to an evaporator (not shown), which constitutes a conduit, via the inlet 330.

The third front-side communication passage 18 c communicates with the second front-side communication passage 18 b and the junction discharge chamber 239. The second rear-side communication passage 20 b communicates with the junction discharge chamber 239 at the front end and opens in the rear end face 23 b of the second cylinder block 23 at the rear end. The second connection passage 37 b extends in the drive shaft axial direction from the front end face 23 a to the rear end face 23 b.

As shown in FIG. 4, the first housing member 17 is secured to the front end face 21 a of the first cylinder block 21 with the projection 21 c of the first cylinder block 21 inserted in the accommodation chamber 170 b. At this time, a first valve assembly plate 39 and a first gasket 40 are held between the rear end face 17 c of the housing main body 17 a and the front end face 21 a of the first cylinder block 21. That is, the first housing member 17 is secured to the front end face 21 a of the first cylinder block 21 with the first valve assembly plate 39 and the first gasket 40 in between. The first valve assembly plate 39 is a thin metal plate. The first gasket 40 is a sheet of, for example, plastic, rubber, or elastomer.

The first valve assembly plate 39 includes a first valve base plate 390, a first suction valve plate 391, a first discharge valve plate 392, and a first retainer plate 393. The first gasket 40 is located on the front surface of the first retainer plate 393 and is located between the rear end face 17 c of the housing main body 17 a and the first retainer plate 393. The first valve base plate 390, the first suction valve plate 391, the first discharge valve plate 392, the first retainer plate 393, and the first gasket 40 extend to the outer peripheries of the housing main body 17 a and the first cylinder block 21. The first gasket 40 may have a size that does not reach the outer peripheries of the housing main body 17 a and the first cylinder block 21. Also, the first gasket 40 may be omitted, and the first suction valve plate 391 or the first retainer plate 393 may be coated with a sealing layer. In this case, the sealing layer functions as a first gasket of the present invention.

The first valve base plate 390, the first discharge valve plate 392, the first retainer plate 393, and the first gasket 40 have first suction holes 390 a, which correspond to the first cylinder bores 211 to 215. The first valve base plate 390, the first suction valve plate 391, and the first gasket 40 have first discharge holes 390 b, which correspond to the first cylinder bores 211 to 215. Further, the first valve base plate 390, the first suction valve plate 391, the first discharge valve plate 392, the first retainer plate 393, and the first gasket 40 have a first suction communication hole 390 c, a first through-hole 390 d, and a first discharge communication hole 390 e.

Each of the first cylinder bores 211 to 215 communicates with the first suction chamber 27 a through the corresponding first suction holes 390 a. Each of the first cylinder bores 211 to 215 also communicates with the first discharge chamber 29 a through the corresponding first discharge holes 390 b. The first suction chamber 27 a and the first connection passage 37 a communicate with each other through the first suction communication hole 390 c. The first front-side communication passage 18 a and the second front-side communication passage 18 b communicate with each other through the first discharge communication hole 390 e.

The first through-hole 390 d receives the first protrusion 170 and the projection 21 c. This causes the first abutting portion 170 a to directly contact the front end face 21 a of the first cylinder block 21. The contact between the first abutting portion 170 a and the front end face 21 a of the first cylinder block 21 will be described below.

The first suction valve plate 391 is located on the rear surface of the first valve base plate 390. The first suction valve plate 391 includes the first suction reed valves 391 a, which are configured to open and close the first suction holes 390 a by elastic deformation. The first discharge valve plate 392 is located on the front surface of the first valve base plate 390. The first discharge valve plate 392 includes the first discharge reed valves 392 a, which are configured to open and close the first discharge holes 390 b by elastic deformation. The first retainer plate 393 is located on the front surface of the first discharge valve plate 392. The first retainer plate 393 limits the maximum opening degree of the first discharge reed valves 392 a.

As shown in FIG. 5, the second housing member 19 is secured to the rear end face 23 b of the second cylinder block 23 with the projection 23 c of the second cylinder block 23 inserted in the pressure regulation chamber 31. At this time, the O-ring 51 a on the projection 23 c seals the boundary between the second protrusion 190 and the projection 23 c to ensure the airtightness of the pressure regulation chamber 31.

The second valve assembly plate 41 and the second gasket 42 are held between the front end face 19 a of the second housing member 19 and the rear end face 23 b of the second cylinder block 23. That is, the second housing member 19 is secured to the rear end face 23 b of the second cylinder block 23 with the second valve assembly plate 41 and the second gasket 42 in between. The second valve assembly plate 41 is a thin metal plate. The second gasket 42 is a sheet of, for example, plastic, rubber, or elastomer.

The second valve assembly plate 41 includes a second valve base plate 410, a second suction valve plate 411, a second discharge valve plate 412, and a second retainer plate 413. The second gasket 42 is located on the rear surface of the second retainer plate 413 and is located between the front end face 19 a of the second housing member 19 and the second retainer plate 413. The second valve base plate 410, the second suction valve plate 411, the second discharge valve plate 412, the second retainer plate 413, and the second gasket 42 extend to the outer peripheries of the second housing member 19 and the second cylinder block 23. The second gasket 42 may have a size that does not reach the outer peripheries of the second housing member 19 and the second cylinder block 23. Also, the second gasket 42 may be omitted, and the second suction valve plate 411 or the second retainer plate 413 may be coated with a sealing layer. In this case, the sealing layer functions as a second gasket of the present invention.

The second valve base plate 410, the second discharge valve plate 412, the second retainer plate 413, and the second gasket 42 have second suction holes 410 a, which correspond to the second cylinder bores 231 to 235. Also, the second valve base plate 410, the second suction valve plate 411, and the second gasket 42 have second discharge holes 410 b, which correspond to the second cylinder bores 231 to 235. Further, the second valve base plate 410, the second suction valve plate 411, the second discharge valve plate 412, the second retainer plate 413, and the second gasket 42 have a second suction communication hole 410 c, a second through-hole 410 d, and a second discharge communication hole 410 e.

Each of the second cylinder bores 231 to 235 communicates with the second suction chamber 27 b through the corresponding second suction holes 410 a. Each of the second cylinder bores 231 to 235 also communicates with the second discharge chamber 29 b through the corresponding second discharge holes 410 b. The second suction chamber 27 b and the second connection passage 37 b communicate with each other through the second suction communication hole 410 c. The first rear-side communication passage 20 a and the second rear-side communication passage 20 b communicate with each other through the second discharge communication hole 410 e.

The second through-hole 410 d receives the second protrusion 190 and the projection 23 c. This causes the second abutting portion 190 a to directly contact the rear end face 23 b of the second cylinder block 23. The contact between the second abutting portion 190 a and the rear end face 23 b of the second cylinder block 23 will be described below.

The second suction valve plate 411 is located on the front surface of the second valve base plate 410. The second suction valve plate 411 includes the second suction reed valves 411 a, which are configured to open and close the second suction holes 410 a by elastic deformation. The second discharge valve plate 412 is located on the rear surface of the second valve base plate 410. The second discharge valve plate 412 includes the second discharge reed valves 412 a, which are configured to open and close the second discharge holes 410 b by elastic deformation. The second retainer plate 413 is located on the rear surface of the second discharge valve plate 412. The second retainer plate 413 limits the maximum opening degree of the second discharge reed valves 412 a.

As shown in FIGS. 1 and 4, the first front-side communication passage 18 a, the first discharge communication hole 390 e, the second front-side communication passage 18 b, and the third front-side communication passage 18 c constitute a first discharge communication passage 18. As shown in FIGS. 1 and 5, the first rear-side communication passage 20 a, the second discharge communication hole 410 e, and the second rear-side communication passage 20 b constitute a second discharge communication passage 20.

As shown in FIGS. 1, 4, and 5, the first and second connection passages 37 a, 37 b and the first and second suction communication holes 390 c, 410 c connect the first and second suction chambers 27 a, 27 b to the swash plate chamber 33. This substantially equalizes the pressure in the first and second suction chambers 27 a, 27 b with the pressure in the swash plate chamber 33. Low-pressure refrigerant gas delivered from the evaporator flows into the swash plate chamber 33 via the inlet 330. As a result, the pressure in the swash plate chamber 33 and the pressure in the first and second suction chambers 27 a, 27 b are lower than the pressure in the first and second discharge chambers 29 a, 29 b.

The drive shaft 3 includes a drive shaft main body 30, a first support member 43 a, and a second support member 43 b. The drive shaft main body 30 includes a first small diameter portion 30 a on the front side. The drive shaft main body 30 includes a second small diameter portion 30 b on the rear side. The drive shaft main body 30 extends from the front side toward the rear side of the housing 1. The drive shaft main body 30 is located in the housing 1 and is inserted in the shaft sealing device 25 and the first and second plain bearings 22 a, 22 b. Thus, the drive shaft main body 30, or the drive shaft 3, is rotationally supported by the housing 1 about the drive shaft axis O. The front end of the drive shaft main body 30 is located in the boss 17 b. The rear end of the drive shaft main body 30 projects into the pressure regulation chamber 31.

As shown in FIGS. 1 and 2, the swash plate 5, the link mechanism 7, and the actuator 13 are assembled to the drive shaft main body 30. The swash plate 5, the link mechanism 7, and the actuator 13 are arranged in the swash plate chamber 33.

The drive shaft main body 30 has a threaded portion 3 a at the front end. The drive shaft 3 is coupled to a pulley or an electromagnetic clutch (neither is shown) through the threaded portion 3 a.

As shown in FIG. 4, the first support member 43 a is press fitted to the first small diameter portion 30 a of the drive shaft main body 30 and is supported by the first plain bearing 22 a in the first shaft hole 21 d. The first support member 43 a has a first flange 430 on the rear side. The first support member 43 a has an attachment portion (not shown), into which a second pin 47 b, which will be discussed below.

The first flange 430 and the front wall of the first recess 21 f hold the first thrust bearing 35 a with respect to the drive shaft axial direction. The outer diameter of the first flange 430 is larger than the inner diameter of the first thrust bearing 35 a and is smaller than the outer diameter of the first thrust bearing 35 a. Thus, the first thrust bearing 35 a contacts the first flange 430 only in a radially inner part of the second race 352. On the other hand, the inner diameter of the first recessed surface 21 g in the front wall of the first recess 21 f is larger than the inner diameter of the first thrust bearing 35 a and is smaller than the outer diameter of the first thrust bearing 35 a. Thus, the first thrust bearing 35 a contacts the front wall of the first recess 21 f only in a radially outer part of the first race 351.

More specifically, as shown in FIG. 6, the first thrust bearing 35 a contacts the front wall of the first recess 21 f in an annular area L2, which is a radially outer part of an entire annular area L1 of the first race 351. The area L2 corresponds to a first contact portion. The first thrust bearing 35 a contacts the first flange 430 at an annular area L3, which is radially inner part of the second race 352. In this manner, the first thrust bearing 35 a is preloaded to a predetermined value when bearing thrust acting on the drive shaft 3 during operation of the compressor.

As shown in FIG. 8, an imaginary first circumcircle S1, the center of which coincides with the drive shaft axis O, is defined in the first cylinder block 21. The first circumcircle S1 is a circumcircle of the group of the five first cylinder bores 211 to 215. The first circumcircle S1 contacts the first cylinder bores 211 to 215 at positions in the first cylinder bores 211 to 215 that are farthest from the drive shaft axis O. Also, a first imaginary S2 is defined that is coaxial with the first circumcircle S1 and passes through the centers of the first cylinder bores 211 to 215. Further, an imaginary first incircle S3 is defined that is coaxial with the first circumcircle S1 and the first imaginary circle S2. The first incircle S3 is an incircle of the group of the first cylinder bores 211 to 215. The first incircle S3 contacts the first cylinder bores 211 to 215 at positions in the first cylinder bores 211 to 215 that are closest to the drive shaft axis O. For the illustrative purposes, the first support member 43 a is not illustrated in FIG. 8. The same applies to FIGS. 12 and 13, which will be discussed below.

As shown in FIG. 4, the first housing member 17 and the first cylinder block 21 are secured to each other with the first valve assembly plate 39 and the first gasket 40 in between. Accordingly, the first protrusion 170, which is provided on the first housing member 17, is located inside the first circumcircle S1, the first imaginary circle S2, and the first incircle S3 as shown in FIG. 8. This causes the first abutting portion 170 a of the first protrusion 170 to directly contact the front end face 21 a of the first cylinder block 21 in the drive shaft axial direction.

More specifically, when the first thrust bearing 35 a and the first abutting portion 170 a are viewed in a direction D1, which is parallel with the axis O of the drive shaft 3 shown in FIG. 4, the entire area L1 of the first thrust bearing 35 a and the area L4 of the first abutting portion 170 a have a relative positional relationship illustrated in FIG. 8. In FIG. 8, the entire area L1 of the first thrust bearing 35 a is an annular area between two concentric circles represented by solid lines A1, A2. In FIG. 8, the area L4 of the first abutting portion 170 a is an annular area between two concentric circles represented by broken lines B1, B2. The area L4 of the first abutting portion 170 a overlaps the entire L1 of the first thrust bearing 35 a with respect to the drive shaft axial direction.

The area L2, in which the first race 351 and the front wall of the first recess 21 f contact each other in the direction D1, and the area L4 of the first abutting portion 170 a have a relative positional relationship shown in FIG. 9. In FIG. 9, the area L2 is an annular area between two concentric circles represented by the solid line A1 and a broken line B3. As in FIG. 8, the area L4 is an annular area between two concentric circles represented by the broken lines B1, B2. As shown in FIG. 9, a part of the area L4 overlaps the area L2 in a cross-hatched area L9 with respect to the drive shaft axial direction. Specifically, the area L9 is an annular area between two concentric circles represented by the broken lines B1, B3. For the illustrative purposes, the first cylinder block 21 and the first support member 43 a are not illustrated in FIG. 9.

Further, as shown in FIG. 6, a part of the area L4 that does not overlap the area L2 overlaps the area L3, in which the second race 352 and the first flange 430 contact each other with respect to the drive shaft axial direction, in an area L10.

Since the first housing member 17 and the first cylinder block 21 are both made of metal, the first housing member 17 and the first cylinder block 21 make metal-to-metal contact in the area L4 via the first abutting portion 170 a. That is, the first housing member 17 and the first cylinder block 21 make metal-to-metal contact. The first protrusion 170 thus reinforces the part of the first cylinder block 21 that supports the first thrust bearing 35 a.

As shown in FIGS. 1 and 2, the front end of a restoration spring 44 a is inserted in the first support member 43 a. The restoration spring 44 a extends in the drive shaft axial direction O from the flange 430 toward the swash plate 5.

As shown in FIG. 5, the second support member 43 b is press fitted to the rear part of the second small diameter portion 30 b of the drive shaft main body 30 and is supported by the second plain bearing 22 b in the second shaft hole 23 d. The second support member 43 b has a second flange 431 at the front end. Further, O-rings 51 b, 51 c are provided in a part of the second support member 43 b that is rearward of the second flange 431. The O-rings 51 b, 51 c seal the boundary between the pressure regulation chamber 31 and the second recess 23 f, and thus seals the boundary between the pressure regulation chamber 31 and the swash plate chamber 33.

The second flange 431 and the rear wall of the second recess 23 f hold the second thrust bearing 35 b with respect to the drive shaft axial direction. The outer diameter of the second flange 431 is larger than the inner diameter of the second thrust bearing 35 b and is smaller than the outer diameter of the second thrust bearing 35 b. Thus, the second thrust bearing 35 b contacts the second flange 431 only at a radially inner part of the second race 355. On the other hand, the inner diameter of the second recessed surface 23 g in the rear wall of the second recess 23 f is larger than the inner diameter of the second thrust bearing 35 b and is smaller than the outer diameter of the second thrust bearing 35 b. Thus, the second thrust bearing 35 b contacts the rear wall of the second recess 23 f only at a radially outer part of the first race 354.

More specifically, the second thrust bearing 35 b contacts the rear wall of the second recess 23 f in an annular area L6, which is a radially outer part of an entire annular area L5 of the first race 354. The area L6 corresponds to a second contact portion. The second thrust bearing 35 b contacts the second flange 431 at an annular area L7, which is radially inner part of the second race 355. In this manner, the second thrust bearing 35 b is preloaded to a predetermined value when bearing thrust acting on the drive shaft 3 during operation of the compressor.

As shown in FIG. 10, an imaginary second circumcircle S4, the center of which coincides with the drive shaft axis O, is defined in the second cylinder block 23. The second circumcircle S4 is a circumcircle of the group of the five second cylinder bores 231 to 235. Also, a second imaginary S5 is defined that is coaxial with the second circumcircle S4 and passes through the centers of the second cylinder bores 231 to 235. Further, an imaginary second incircle S6 is defined that is coaxial with the second circumcircle S4 and the second imaginary circle S5. The second incircle S6 is an incircle of the group of the second cylinder bores 231 to 235. The second incircle S6 contacts the second cylinder bores 231 to 235 at positions in the second cylinder bores 231 to 235 that are closest to the drive shaft axis O. For the illustrative purposes, the second support member 43 b is not illustrated in FIG. 10.

As shown in FIG. 5, the second housing member 19 and the second cylinder block 23 are secured to each other with the second valve assembly plate 41 and the second gasket 42 in between. Accordingly, the second protrusion 190, which is provided on the second housing member 19, is located inside the second circumcircle S4, the second imaginary circle S5, and the second incircle S6 as shown in FIG. 9. This causes the second abutting portion 190 a of the second protrusion 190 to directly contact the rear end face 23 b of the second cylinder block 23 with respect to the drive shaft axial direction.

More specifically, when the second thrust bearing 35 b and the second protrusion 190 are viewed in a direction D2, which is parallel with the axis O of the drive shaft 3 shown in FIG. 5, the entire area L5 of the second thrust bearing 35 b and the area L8 of the second protrusion 190 have a relative positional relationship illustrated in FIG. 10. In FIG. 10, the entire area L5 of the second thrust bearing 35 b is an annular area between two concentric circles represented by solid lines A3, A4. In FIG. 9, the area L8 of the second abutting portion 190 a is an annular area between two concentric circles represented by broken lines B4, B5. The area L8 of the second abutting portion 190 a overlaps the entire L5 of the second thrust bearing 35 b with respect to the drive shaft axial direction.

The area L6, in which the first race 354 and the rear wall of the second recess 23 f contact each other in the direction D2, and the area L8 of the second abutting portion 190 a have a relative positional relationship shown in FIG. 11. In FIG. 11, the area L6 is an annular area between two concentric circles represented by the solid line A4 and a broken line B6. As in FIG. 10, the area L8 is an annular area between two concentric circles represented by the broken lines B4, B5. As shown in FIG. 11, a part of the area L8 overlaps the area L6 in a cross-hatched area L11 with respect to the drive shaft axial direction. Specifically, the area L11 is an annular area between two concentric circles represented by the broken lines B4, B6. For the illustrative purposes, the second cylinder block 23 and the second support member 43 b are not illustrated in FIG. 11.

As shown in FIG. 7, the area L8 does not overlap the area L7, in which the second race 355 and the second flange 431 contact each other, with respect to the drive shaft axial direction.

Since the second housing member 19 and the second cylinder block 23 are both made of metal, the second housing member 19 and the second cylinder block 23 make metal-to-metal contact in the area L8 via the second protrusion 190. The second protrusion 190 thus reinforces the part of the second cylinder block 23 that supports the second thrust bearing 35 b. That is, the second housing member 19 and the second cylinder block 23 make metal-to-metal contact.

As shown in FIGS. 1 and 2, the swash plate 5 is shaped as a flat annular plate and has a front surface 5 a and a rear surface 5 b. The front surface 5 a faces forward in the swash plate chamber 33. The rear surface 5 b faces rearward in the swash plate chamber 33.

The swash plate 5 has a ring plate 45. The ring plate 45 is shaped as a flat annular plate and has a receiving hole 45 a at the center. The drive shaft main body 30 is inserted in the receiving hole 45 a in the swash plate chamber 33 so that the swash plate 5 is mounted to the drive shaft 3. The ring plate 45 has a coupling portion (not shown), which is coupled to traction arms 132, which will be discussed below.

The link mechanism 7 has a lug arm 49. The lug arm 49 is arranged forward of the swash plate 5 in the swash plate chamber 33 and located between the swash plate 5 and the first support member 43 a. The lug arm 49 substantially has an L shape as a whole. A weight portion 49 a is provided in a rear part the lug arm 49. The weight portion 49 a extends in the circumferential direction of the actuator 13 to cover substantially a half of the circumference of the actuator 13. The weight portion 49 a may be designed to have any suitable shape.

The lug arm 49 is coupled, in a rear part, to the ring plate 45 with a first pin 47 a. This configuration supports the lug arm 49 to allow the lug arm 49 to pivot about the axis of the first pin 47 a, which is a first pivot axis M1, relative to the ring plate 45, or, in other words, relative to the swash plate 5. The first pivot axis M1 extends perpendicular to the axis O of the drive shaft 3.

The lug arm 49 is coupled, in a front part, to the first support member 43 a with the second pin 47 b. This configuration supports the lug arm 49 to allow the lug arm 49 to pivot about the axis of the second pin 47 b, which is a second pivot axis M2, relative to the first support member 43 a, or in other words, relative to the drive shaft 3. The second pivot axis M2 extends parallel with the first pivot axis M1. Further, the lug arm 49, the first and second pins 47 a, 47 b constitute the link mechanism 7.

The weight portion 49 a extends in the rear part of the lug arm 49, that is, on a side opposite of the first pivot axis M1 to the second pivot axis M2. The lug arm 49 is supported by the ring plate 45 with a first pin 47 a. The weight portion 49 a extends through a groove portion 45 b of the ring plate 45 and is located rearward of the ring plate 45, that is, rearward of the swash plate 5. The centrifugal force produced by rotation of the swash plate 5 about the drive shaft axis O is applied to the weight portion 49 a on the rear side of the swash plate 5.

Since the swash plate 5 and the drive shaft 3 are coupled to each other by the link mechanism, the swash plate 5 is allowed to rotate together with the drive shaft 3. The inclination angle of the swash plate 5 is changed from the minimum inclination angle shown in FIG. 1 to the maximum inclination angle shown in FIG. 2 through pivoting actions of the opposite ends of the lug arm 49 about the first pivot axis M1 and the second pivot axis M2.

As shown in FIGS. 1 and 2, the pistons 9 each include a first piston head 9 a on the front side and a second piston head 9 b on the rear side. The first piston heads 9 a are reciprocally accommodated in the first cylinder bores 211 to 215. The first piston heads 9 a and the first valve assembly plate 39 define first compression chambers 53 a in the first cylinder bores 211 to 215. The second piston heads 9 b are reciprocally accommodated in the second cylinder bores 231 to 235. The second piston heads 9 b and the second valve assembly plate 41 define second compression chambers 53 b in the second cylinder bores 231 to 235.

Each double-headed piston 9 has an engagement portion 9 c at the center. Each engagement portion 9 c accommodates semispherical shoes 11 a, 11 b. Each shoe 11 a slides on the front surface 5 a of the swash plate 5. In contrast, each shoe 11 b slides on the rear surface 5 b of the swash plate 5. The shoes 11 a, 11 b convert rotation of the swash plate 5 into reciprocation of the double-headed pistons 9. The shoes 11 a, 11 b correspond to a conversion mechanism. The first and second piston heads 9 a, 9 b thus reciprocate in the first and second cylinder bores 211 to 215 and 231 to 235 by a stroke corresponding to the inclination angle of the swash plate 5.

The compressor shifts the top dead center positions of the first piston heads 9 a and the second piston heads 9 b by varying the stroke of the double-headed pistons 9 in accordance with changes in the inclination angle of the swash plate 5. Specifically, the top dead center position of each second piston head 9 b is shifted by a greater amount than the top dead center position of each first piston head 9 a as the inclination angle of the swash plate 5 is decreased.

The actuator 13 is arranged in the swash plate chamber 33. The actuator 13 is located rearward of the swash plate 5 in the swash plate chamber 33 and is allowed to enter the second recess 23 f. The actuator 13 includes a movable body 13 a, a partition body 13 b, and a control pressure chamber 13 c. The control pressure chamber 13 c is defined between the movable body 13 a and the partition body 13 b.

The movable body 13 a includes a rear wall 130, a circumferential wall 131, and a pair of traction arms 132. In FIGS. 1 and 2, only one of the traction arms 132 is illustrated.

The rear wall 130 is located in the rear part of the movable body 13 a and extends radially away from the drive shaft axis O. The rear wall 130 has a receiving hole 130 a, which receives the second small diameter portion 30 b of the drive shaft main body 30. An O-ring 51 d is fitted in the receiving hole 130 a. The circumferential wall 131 is continuous with the periphery of the rear wall 130 and extends toward the front of the movable body 13 a. The traction arms 132 are located on the front end of the circumferential wall 131 and on opposite sides of the drive shaft axis O. The traction arms 132 project toward the front of the movable body 13 a. The rear wall 130, the circumferential wall 131, and the traction arms 132 constitute the cylindrical shape with a closed end of the movable body 13 a.

The partition body 13 b has a disk-like shape the diameter of which is substantially equal to the inner diameter of the movable body 13 a. The partition body 13 b has a receiving hole 133 at the center. An O-ring 51 e is fitted on the outer circumference of the partition body 13 b.

An inclination reducing spring 44 b is provided between the partition body 13 b and the ring plate 45. Specifically, the rear end of the inclination reducing spring 44 b is arranged to contact the partition body 13 b, and the front end of the inclination reducing spring 44 b is arranged to contact the ring plate 45.

The receiving hole 130 a of the movable body 13 a receives the second small diameter portion 30 b of the drive shaft main body 30. The movable body 13 a is thus allowed to move the second small diameter portion 30 b along the drive shaft axis O. In contrast, the second small diameter portion 30 b is press fitted in the receiving hole 133 of the partition body 13 b to be allowed to rotate integrally with the drive shaft 3. The partition body 13 b may also be fitted about the second small diameter portion 30 b to be movable along the drive shaft axis O.

The partition body 13 b is arranged in the movable body 13 a rearward of the swash plate 5 and is surrounded by the circumferential wall 131. Thus, when the movable body 13 a moves along the drive shaft axis O, the inner circumferential surface of the circumferential wall 131 of the movable body 13 a slides on the outer circumferential surface of the partition body 13 b.

Since the partition body 13 b is surrounded by the circumferential wall 131, the movable body 13 a and the partition body 13 b define the control pressure chamber 13 c in between. The control pressure chamber 13 c is partitioned from the swash plate chamber 33 by the rear wall 130, the circumferential wall 131, and the partition body 13 b.

The traction arms 132 are coupled to the ring plate 45 with a third pin 47 c. In this manner, the swash plate 5 is supported by the movable body 13 a to be allowed to pivot about the axis of the third pin 47 c, which is an operation axis M3. The operation axis M3 extends parallel with the first and second pivot axes M1, M2. The movable body 13 a is thus held in a state coupled to the swash plate 5. This causes the partition body 13 b and the swash plate 5 to face each other.

The second small diameter portion 30 b has an axial passage 3 b, which extends forward from the rear end along the drive shaft axis O, and a radial passage 3 c, which extends radially from the front end of the axial passage 3 b and has an opening in the outer peripheral surface of the drive shaft main body 30. The rear end of the axial passage 3 b communicates with the pressure regulation chamber 31. The radial passage 3 c communicates with the control pressure chamber 13 c. Thus, the control pressure chamber 13 c communicates with the pressure regulation chamber 31 via the radial passage 3 c and the axial passage 3 b.

As shown in FIG. 3, the control mechanism 15 includes a bleed passage 15 a, a supply passage 15 b, a control valve 15 c, an orifice 15 d, the axial passage 3 b, and the radial passage 3 c.

The bleed passage 15 a is connected to the pressure regulation chamber 31 and the second suction chamber 27 b. The bleed passage 15 a, the axial passage 3 b, and the radial passage 3 c connect the control pressure chamber 13 c, the pressure regulation chamber 31, and the second discharge chamber 29 b with one another. The supply passage 15 b is connected to the pressure regulation chamber 31 and the second discharge chamber 29 b. The supply passage 15 b, the axial passage 3 b, and the radial passage 3 c connect the control pressure chamber 13 c, the pressure regulation chamber 31, and the second discharge chamber 29 b with one another. The supply passage 15 b has the orifice 15 d.

The control valve 15 c is arranged in the bleed passage 15 a. The control valve 15 c is configured to adjust the opening degree of the bleed passage 15 a based on the pressure in the second suction chamber 27 b.

In the compressor shown in FIG. 1, a pipe coupled to the evaporator is connected to the inlet 330, and a pipe coupled to the condenser is coupled to the outlet 230. The condenser is connected to the evaporator via a pipe and an expansion valve. The compressor, the evaporator, the expansion valve, and the condenser constitute the refrigeration circuit of the vehicle air conditioner. The illustration of the evaporator, the expansion valve, the condenser, and the pipes is omitted.

In the compressor having the above-described configuration, the drive shaft 3 rotates to rotate the swash plate 5, thus reciprocating the pistons 9 in the first and second cylinder bores 211 to 215 and 231 to 235. This varies the volumes of the first and second compression chambers 53 a, 53 b in correspondence with the piston stroke. The compressor thus repeatedly performs a suction stroke for drawing in refrigerant gas into the first and second compression chambers 53 a, 53 b, a compression stroke for compressing the refrigerant gas in the first and second compression chambers 53 a, 53 b, and a discharge stroke for discharging the compressed refrigerant gas to the first and second discharge chambers 29 a, 29 b.

The refrigerant gas discharged to the first discharge chamber 29 a reaches the junction discharge chamber 239 via the first discharge communication passage 18. Likewise, the refrigerant gas discharged to the second discharge chamber 29 b reaches the junction discharge chamber 239 via the second discharge communication passage 20. The refrigerant gas that has reached the junction discharge chamber 239 is discharged to the condenser through the outlet 230 and the pipe.

For example, during the suction stroke, the rotor constituted by the swash plate 5, the ring plate 45, the lug arm 49, and the first pin 47 a receive the piston compression force acting to decrease the inclination angle of the swash plate 5. Through such change of the inclination angle of the swash plate 5, displacement control is carried out by selectively increasing and decreasing the stroke of each double-headed piston 9.

More specifically, when the control valve 15 c of the control mechanism 15 shown in FIG. 3 increases the opening degree of the bleed passage 15 a, the pressure in the pressure regulation chamber 31 and thus the pressure in the control pressure chamber 13 c become substantially equal to the pressure in the second suction chamber 27 b. That is, a variable differential pressure, which is the differential pressure between the pressure in the control pressure chamber 13 c and the pressure in the swash plate chamber 33 is decreased. The piston compression force acting on the swash plate 5 thus moves the movable body 13 a of the actuator 13 forward in the swash plate chamber 33 as shown in FIG. 1.

Accordingly, the compression reaction force, which acts on the swash plate 5 via the double-headed pistons 9, urges the swash plate 5 in a direction reducing the inclination angle. Thus, the movable body 13 a is pulled forward in the swash plate chamber 33 by the traction arms 132 at the operation axis M3. This pivots the swash plate 5 clockwise about the operation axis M3, while acting against the urging force of the restoration spring 44 a. Furthermore, the rear end of the lug arm 49 pivots counterclockwise about the first pivot axis M1, and the front end of the lug arm 49 pivots counterclockwise about the second pivot axis M2. The front part of the lug arm 49 thus approaches the first flange 430 of the first support member 43 a. In this manner, the swash plate 5 pivots with the operation axis M3 serving as a point of application and the first pivot axis M1 serving as a fulcrum. This reduces the inclination angle of the swash plate 5 relative to axis O of the drive shaft 3 and reduces the stroke of the double-headed pistons 9. Thus, the displacement of the compressor per rotation of the drive shaft 3 is reduced.

The swash plate 5 of the compressor receives the centrifugal force acting on the weight portion 49 a. Thus, the swash plate 5 of the compressor easily moves in such a direction as to decrease the inclination angle. When the inclination angle of the swash plate 5 is reduced, the ring plate 45 contacts the rear end of the restoration spring 44 a.

When the inclination angle of the swash plate 5 is reduced, and the stroke of the double-headed pistons 9 is reduced, the top dead center position of each second piston head 9 b is separated away from the second valve assembly plate 41. Thus, when the inclination angle of the swash plate 5 approaches zero degrees, compression work is not performed in the second compression chambers 53 b while compression is slightly performed in the first compression chambers 53 a.

In contrast, if the control valve 15 c illustrated in FIG. 3 reduces the opening degree of the bleed passage 15 a, the pressure of the refrigerant gas in the second discharge chamber 29 b increases the pressure in the pressure regulation chamber 31, which increases the pressure in the control pressure chamber 13 c. Accordingly, the variable differential pressure is increased. Thus, in the actuator, the movable body 13 a is moved rearward in the swash plate chamber 33 against the piston compression force acting on the swash plate 5 as shown in FIG. 2.

Accordingly, the movable body 13 a pulls the swash plate 5 rearward in the swash plate chamber 33 through the traction arms 132 at the operation axis M3. This causes the lower end U of the swash plate 5 to pivot counterclockwise about the operation axis M3. Also, the rear end of the lug arm 49 pivots clockwise about the first pivot axis M1 and the front end of the lug arm 49 pivots clockwise about the second pivot axis M2. The front part of the lug arm 49 thus moves away from the first flange 430 of the first support member 43 a. This pivots the swash plate 5 in the opposite direction to the direction in the case where the inclination angle decreases, with the operation axis M3 and the first pivot axis M1 serving as the point of application and the fulcrum, respectively. The inclination angle of the swash plate 5 relative to the axis O of the drive shaft 3 is thus increased. This increases the stroke of the double-headed pistons 9 and thus increases the displacement of the compressor per rotation of the drive shaft 3.

The compressor has the first gasket 40, which is located between the rear end face 17 c of the housing main body 17 a and the front surface of the first retainer plate 393, as shown in FIG. 4. The first gasket 40 extends to the outer peripheries of the first housing member 17 and the first cylinder block 21 to be held by the first housing member 17 and the first cylinder block 21. The gasket 40 thus seals the boundary between the first housing member 17 and the first cylinder block 21. Also, as shown in FIG. 5, the second gasket 42 is located between the front end face 19 a of the second housing member 19 and the rear surface of the second retainer plate 413. The second gasket 42 also extends to the outer peripheries of the second housing member 19 and the second cylinder block 23 to be held by the second housing member 19 and the second cylinder block 23. The gasket 42 thus seals the boundary between the second housing member 19 and the second cylinder block 23.

Accordingly, it is not necessary to seal, with O-rings, the boundary between the first housing member 17 and the first cylinder block 21 or the boundary between the second housing member 19 and the second cylinder block 23. Thus, the first and second housing members 17, 19 and the first and second cylinder blocks 21, 23 do not need to have O-rings or spaces for accommodating O-rings on the outer peripheries, which allows the diameters of the first and second housing members 17, 19 and the first and second cylinder blocks 21, 23 to be reduced.

As shown in FIG. 4, the compressor has the first protrusion 170 on the housing main body 17 a, and the first valve assembly plate 39 and the first gasket 40 have the first through-hole 390 d. When securing the first housing member 17 and the first cylinder block 21 to each other, the first protrusion 170 is inserted in the first through-hole 390 d. This causes the first abutting portion 170 a of the first protrusion 170 to directly contact the front end face 21 a of the first cylinder block 21. That is, the first abutting portion 170 a and the front end face 21 a make metal-to-metal contact. Accordingly, the first housing member 17 and the front end face 21 a of the first cylinder block 21 make metal-to-metal contact with respect to the drive shaft axial direction.

As shown in FIG. 5, the second housing member 19 has the second protrusion 190, and the second valve assembly plate 41 and the second gasket 42 have the second through-hole 410 d. When securing the second housing member 19 and the second cylinder block 23 to each other, the second protrusion 190 is inserted in the second through-hole 410 d. This causes the second abutting portion 190 a of the second protrusion 190 makes metal-to-metal contact with the rear end face 23 b of the second cylinder block 23. Accordingly, the second housing member 19 and the rear end face 23 b of the second cylinder block 23 make metal-to-metal contact with respect to the drive shaft axial direction.

When the first thrust bearing 35 a and the first abutting portion 170 a are viewed in the direction D1 indicated in FIG. 4, the first abutting portion 170 a makes metal-to-metal contact with the front end face 21 a of the first cylinder block 21 in the area L4, which overlaps the first thrust bearing 35 a as shown in FIG. 8. When the second thrust bearing 35 b and the second abutting portion 190 a are viewed in the direction D2 indicated in FIG. 5, the second abutting portion 190 a makes metal-to-metal contact with the rear end face 23 b of the second cylinder block 23 in the area L8, which overlaps the second thrust bearing 35 b as shown in FIG. 10.

Thus, the first housing member 17 reliably reinforces the first cylinder block 21 through the first abutting portion 170 a at a position in the first cylinder block 21 that is close to a part supporting the first thrust bearing 35 a. Also, the second housing member 19 reliably reinforces the second cylinder block 23 through the second abutting portion 190 a at a position in the second cylinder block 23 that is close to a part supporting the second thrust bearing 35 b.

Further, when the area L2, in which the first race 351 and the front wall of the first recess 21 f contact each other, and the area L4 of the first abutting portion 170 a are viewed in the direction D1 indicated in FIG. 4, a part of the area L4 overlaps the area L2 in the area L9 with respect to the drive shaft axial direction as shown in FIG. 9. Likewise, when the area L6, in which the first race 354 and the rear wall of the second recess 23 f contact each other, and the area L8 of the second abutting portion 190 a are viewed in the direction D2 indicated in FIG. 5, which is parallel with the axis O of the drive shaft 3, a part of the area L8 overlaps the area L6 in the area L11 with respect to the drive shaft axial direction as shown in FIG. 11.

Accordingly, the support stiffness of the housing 1 in the drive shaft axial direction is not easily lowered, and the preloads on the first and second thrust bearings 35 a, 35 b are reliably maintained in a proper range.

The compressor of the present embodiment suppresses vibrations and accompanying noise during operation, while reducing the size and the manufacturing costs.

Particularly, the compressor includes the link mechanism 7, the actuator 13, and the control mechanism 15, which allows the displacement of refrigerant gas per rotation of the drive shaft 3 to be changed in accordance with the driving state of the vehicle. To install the link mechanism 7 and the actuator 13 in the compressor, the first recess 21 f in the first cylinder block 21 and the second recess 23 f in the second cylinder block 23 expand the swash plate chamber 33. Thus, there is a concern that the stiffness of parts of the first and second cylinder blocks 21, 23 that support the first and second thrust bearings 35 a, 35 b may be easily lowered. In this regard, the first housing member 17 reinforces the first cylinder block 21 through the first abutting portion 170 a of the first protrusion 170, and the second housing member 19 reinforces the second cylinder block 23 through the second abutting portion 190 a of the second protrusion 190. Therefore, even though the first and second recesses 21 f, 23 f increase the size of the swash plate chamber 33, the support stiffness of the housing 1 in the drive shaft axial direction is not easily lowered.

First Modification

In a compressor according to a first modification, the housing main body 17 a of the first housing member 17 has five first protrusions 171 to 175, which are integrated with the housing main body 17 a. The first protrusions 171 to 175 have columnar shapes. The first protrusions 171 to 175 may have polygonal cross-sections. The number of the first protrusions 171 to 175 may be designed to any number as necessary.

In the housing main body 17 a, the first protrusions 171 to 175 are arranged on the same circle and at equal angular intervals at positions radially outward of the position of the first protrusion 170 of the above illustrated embodiment, more specifically, at positions between the first circumcircle S1 and the first imaginary circle S2. Although not illustrated, the first protrusions 171 to 175 protrude further rearward over the rear end face 17 c of the housing main body 17 a like the above described first protrusion 170. The rear end face of the first protrusion 171 is a first abutting portion 171 a. Likewise, the rear end faces of the first protrusions 172 to 175 respectively constitute first abutting portions 172 a to 175 a. Since the first protrusions 171 to 175 have columnar shapes, the first abutting portions 171 a to 175 a each have a circular shape.

Although not illustrated, the first valve assembly plate 39 and the first gasket 40 each have through holes for receiving the first protrusions 171 to 175. Also, although not illustrated, the second housing member 19 have five second protrusions, and the front end face of each second protrusion is a second abutting portion. The other components of the compressor of the first modification are configured identically with the corresponding components of the compressor of the embodiment. Accordingly, these components are identified by the same reference numbers, and detailed description thereof is omitted herein.

The first housing member 17 and the first cylinder block 21 are secured to each other with the first valve assembly plate 39 and the first gasket 40 held in between, so that the first abutting portions 171 a to 175 a make metal-to-metal contact with the front end face 21 a of the first cylinder block 21 at positions between the first circumcircle S1 and the first imaginary circle S2. Although not illustrated, the second housing member 19 and the second cylinder block 23 are secured to each other with the second valve assembly plate 41 and the second gasket 42 held in between, so that the second abutting portions make metal-to-metal contact with the rear end face 23 b of the second cylinder block 23 at positions between the second circumcircle S4 and the first imaginary circle S5.

In the compressor of the first modification also, the first housing member 17 reliably reinforces the first cylinder block 21 via the first abutting portions 171 a to 175 a of the first protrusions 171 to 175 at a position in the first cylinder block 21 that is relatively close to a part supporting the first thrust bearing 35 a, and the second housing member 19 reliably reinforces the second cylinder block 23 through the second abutting portions of the second protrusions (not shown). Therefore, the compressor operates in the same manner as the compressor of the above illustrated embodiment.

Second Modification

In a compressor according to a second modification, the first protrusions 171 to 175 of the first modification are changed as shown in FIG. 13. In the second modification, the first protrusions 171 to 175 are located in the housing main body 17 a at positions closer to the drive shaft axis O than the first protrusions 171 to 175 of the compressor according to the first modification, that is, between the first imaginary circle S2 and the first incircle S3. Accordingly, the first abutting portions 171 a to 175 a make metal-to-metal contact with the front end face 21 a of the first cylinder block 21 at positions between the first imaginary circle S2 and the first incircle S3. Also, in the second modification, the positions of the second protrusions of the second housing member 19 according to the first modification are changed as in the case of the first protrusions 171 to 175. The other structures of the compressor are the same as the corresponding structures of the compressor of the embodiment and the compressor of the first modification.

Therefore, the compressor operates in the same manner as the compressor of the above illustrated embodiment.

Although only the embodiment and the first and second modifications of the present invention have been described so far, the present invention is not limited to the embodiment and the first and second modifications, but may be modified as necessary without departing from the scope of the invention.

For example, the first protrusions 170 to 175 of the embodiment and the first and second modifications may be used in combination as necessary and provided between a first housing member and a first cylinder block. The same applies to the second abutting portions.

The first protrusion 170 of the embodiment may be increased in the diameter within the range inside the first incircle S3, such that the first abutting portion 170 a makes metal-to-metal contact with the front end face 21 a of the first cylinder block 21 at a position where the first abutting portion 170 a does not overlap the first thrust bearing 35 a with respect to the drive shaft axial direction. The same applies the second abutting portion 190 a of the second protrusion 190 of the embodiment.

The first protrusion 170 may be omitted from the housing main body 17 a of the embodiment, and the projection 21 c of the first cylinder block 21 may be extended toward the first housing member 17 to be contactable with the housing main body 17 a. In this case, the front end face of the projection 21 c is a first contact surface, which makes metal-to-metal contact with the first housing member 17. Thus, the first housing member 17 reliably reinforces the first cylinder block 21 at a position in the first cylinder block 21 that is close to a part supporting the first thrust bearing 35 a. Likewise, the second protrusion 190 may be omitted from the second housing member 19, and the projection 23 c of the second cylinder block 23 may be extended toward the second housing member 19 to be contactable with the second housing member 19. In this case, the rear end face of the projection 23 c is a second contact surface, which makes metal-to-metal contact with the second housing member 19. Thus, the second housing member 19 reliably reinforces the second cylinder block 23 at a position in the second cylinder block 23 that is close to a part supporting the second thrust bearing 35 b.

In the compressor of the embodiment, the first protrusion 170 is integrated with the first housing member 17, and the second protrusion 190 is integrated with the second housing member 19. Instead, a cylindrical metal spacer may be provided between the first housing member 17 and the first cylinder block 21 and between the second housing member 19 and the second cylinder block 23, and the spacers may be used as first and second abutting portions. The same applies the compressors of the first and second modifications.

The link mechanism 7, the actuator 13, and the control mechanism 15 may be omitted from the compressor, and the displacement per rotation of the drive shaft 3 may be fixed.

Regarding the control mechanism 15, the control valve 15 c may be provided in the supply passage 15 b, and the orifice 15 d may be provided in the bleed passage 15 a. The configuration allows the control valve 15 c to adjust the opening degree of the supply passage 15 b. This allows the pressure of the refrigerant gas in the second discharge chamber 29 b to promptly increase the pressure in the control pressure chamber 13 c and to promptly increase the displacement.

The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims. 

1. A double-headed piston type swash plate compressor comprising: a first cylinder block, which is made of metal and has a plurality of first cylinder bores; a first housing member, which is made of metal and arranged on a first side of the first cylinder block; a first gasket, which is arranged between the first housing member and the first cylinder block and seals a boundary between the first housing member and the first cylinder block; a second cylinder block, which is made of metal and is arranged on a second side of the first cylinder block that is opposite to the first side, wherein the second cylinder block has a plurality of second cylinder bores and, together with the first cylinder block, defines a swash plate chamber; a second housing member, which is made of metal, wherein, when a side of the second cylinder block that faces the first cylinder block is defined as a first side, the second housing member is arranged on a second side of the second cylinder block that is opposite to the first side; a second gasket, which is arranged between the second cylinder block and the second housing member and seals a boundary between the second cylinder block and the second housing member; a drive shaft, which is rotationally supported by the first cylinder block and the second cylinder block; a swash plate, which is rotational in the swash plate chamber by rotation of the drive shaft; double-headed pistons, which are reciprocal in the first cylinder bores and the second cylinder bores by rotation of the swash plate; a first thrust bearing, which is arranged between the first cylinder block and the drive shaft and bears thrust acting on the drive shaft; a second thrust bearing, which is arranged between the second cylinder block and the drive shaft and bears thrust acting on the drive shaft; a first abutting portion, wherein, when a circumcircle of the group of the first cylinder bores is defined as a first circumcircle, the first abutting portion is located between the first housing member and the first cylinder block and inside the first circumcircle, and the first abutting portion causes the first housing member and the first cylinder block to make metal-to-metal contact; and a second abutting portion, wherein, when a circumcircle of the group of the second cylinder bores is defined as a second circumcircle, the second abutting portion is located between the second housing member and the second cylinder block and inside the second circumcircle, and the second abutting portion causes the second housing member and the second cylinder block to make metal-to-metal contact.
 2. The double-headed piston type swash plate compressor according to claim 1, wherein the first abutting portion is located inside a first imaginary circle, which passes through centers of the first cylinder bores, and the second abutting portion is located inside a second imaginary circle, which passes through centers of the second cylinder bores.
 3. The double-headed piston type swash plate compressor according to claim 2, wherein when an incircle of the group of the first cylinder bores is defined as a first incircle, the first abutting portion is located inside the first incircle, and when an incircle of the group of the second cylinder bores is defined as a second incircle, the second abutting portion is located inside the second incircle.
 4. The double-headed piston type swash plate compressor according to claim 3, wherein the first thrust bearing and the first cylinder block contact each other at a first contact portion, the second thrust bearing and the second cylinder block contact each other at a second contact portion, when the first contact portion and the first abutting portion are viewed in an axial direction of the drive shaft, at least a part of the first abutting portion is in a position overlapping the first contact portion, and when the second contact portion and the second abutting portion are viewed in the drive shaft axial direction, at least a part of the second abutting portion is in a position overlapping the second contact portion.
 5. The double-headed piston type swash plate compressor according to claim 1, further comprising a link mechanism, which is located in the swash plate chamber and between the drive shaft and the swash plate, wherein the link mechanism allows an inclination angle of the swash plate to be changed relative to a direction perpendicular to an axial direction of the drive shaft, wherein the double-headed pistons are reciprocal in the first and second cylinder bores by a stroke corresponding to the inclination angle of the swash plate.
 6. The double-headed piston type swash plate compressor according to claim 5, further comprising: an actuator, which is located in the swash plate chamber and configured to change the inclination angle; and a control mechanism, which controls the actuator, wherein the actuator includes a partition body provided on the drive shaft, a movable body, which is coupled to the swash plate and fitted about the drive shaft to be movable in the drive shaft axial direction, and a control pressure chamber, which is defined by the partition body and the movable body, wherein the control pressure chamber uses an internal pressure thereof to move the movable body. 